<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>all</title>
</head>
<body>
<!-- 处理图片的请求体 必须加 enctype="multipart/form-data"-->
<form action="/receive" method="post" enctype="multipart/form-data">
    用户名:<input type="text" name="username"><br>
    头像:<input type="file" name="pic"><br>
    <button>提交</button>
</form>
</body>
</html>